The official intensity forecast calls for Earl to strengthen to 145 mph (Category 4) by tomorrow afternoon. Given that the intensity forecasts for tropical cyclones, though improving, are still less than reliable at times, this expectation should be treated with caution.

Computer model track guidance continues to be moderately clustered around the idea that Earl will indeed recurve out to sea and miss the U.S. coastline, its center bypassing the eastern tip of the Outer Banks of North Carolina by roughly 150 miles at closest approach just after midnight Friday morning.

Arrows represent upper-level winds projected by the GFS forecast model for early Friday as Earl nears the East Coast. Credit: University of Wyoming.

The ultimate track will be heavily influenced by the timing of an upper-level area of low pressure and associated dip in the jet stream heading eastward from the Northern Plains, and the resulting upper-level winds from the west and northwest over the East Coast. As shown in the forecast map for early Friday (at right), winds from the northwest at high altitudes should be in place across the Carolinas, enough so to deflect Earl back out to sea.

Although the weather models are in reasonably good agreement that the upper-level low will arrive in time to deny a direct hit, typical four-day forecast errors (for both tropical cyclones and upper-level lows) are large enough that residents along the East Coast from Jacksonville, Fla., to Cape Cod, Mass., should pay close attention to the situation.

Keep reading for more on Earl's future and its potential East Coast impacts...

Latest National Hurricane Center forecast track for Earl.

Earl is a moderately large hurricane with sustained hurricane-force winds (74 mph and higher) extending roughly 30-40 miles to the west of its center, and sustained tropical storm-force winds (39 mph and higher) reaching out perhaps 120-140 miles west of center. So even if Earl follows the center line of the official track as currently predicted, tropical storm-force wind gusts and rain squalls could brush the Outer Banks.

Fortunately, the western sides of northward moving tropical cyclones that closely approach the continental U.S. are often dramatically weaker than their eastern sides. These systems, owing to their close proximity to land, often ingest a nontropical offshore flow that tends to weaken the western periphery perhaps more than is often expected.

As Earl moves northward later Friday, the storm is still expected to remain off the Northeast U.S. Coast. Fortunately, cooler ocean waters and strengthening winds aloft should begin to weaken Earl rapidly once it gets north of 40 degrees latitude (roughly the latitude of New York City), though gusty winds and rain squalls may brush Cape Cod.

Rough seas and dangerous rip currents, both from Hurricane Danielle which continues to move away from the U.S. and eventually from Hurricane Earl, are possible all along the Eastern Seaboard for the next several days into the holiday weekend.

These storms would be measurably weaker were it not for all the republican hot air being blown around the beltway these days. Of course they say the same things about us. Only the kids at Fox Snews seem to be in denial over climate change but they are so far out of touch Darwinism will render them extinct anyway.
Seriously though, no matter your politics or beliefs, we are in for a rough few months from weather and lets all be careful out there so we can resume the arguments at a future time.

In this case, an increase in cloud cover would lower temps a bit. Otherwise not much relief from the heat. The northerly flow on the west side of Earl that the DC area might experience will unfortunatly not be attached to a cooler airmass. Often times, the air immediately surrounding a well-developed tropical cyclone is clear and hot, owing to the sinking air on its immediate periphery.

It looks like you'll have to wait until the weekend for some cooling, as a strong cold front should surge through the area. That northerly flow behind the front *will* be attached to a cooler airmass.

On the projected track, wind impact will be minimal. Only in the core of the hurricane (less than 50 miles from the center) will winds be a problem. And that should remain well offshore. Too early to tell if you'll get rain, with some cloudiness a better bet at this time.

It's waaaayyyy too early for any meteorologist--amateur or otherwise--to say with much certainty whether this storm will affect our region...and how much. It could remain well out to sea, or on the other end of the spectrum areas of the NC and Virginia coastline, as well as the Chesapeake bay and Eastern Shore could get hammered.

As someone who has seen/been in hurricanes, having lived in Miami--these things have a mind of their own. If there is a big storm in the vicinity, pay attention. And I would say a cat 4 is a big storm. Bottom line, the accuracy of hurricane forecasting is terrible until about 48 hours out, then it becomes quite accurate.

Not to pick on Greg, but per my previous post re the inaccuracy of hurricane forecasting, his comment less than three hours ago, "The official intensity forecast calls for Earl to strengthen to 145 mph (Category 4) by tomorrow afternoon.", has already been proved incorrect. The storm was upgraded to a cat 4 30 minutes ago--a full day ahead of time.

you're right to point out that there's alot of wiggle room in the forecast for potential impacts of Earl.

But ensemble spread from the track models is clustered tightly enough to say something meaningful and useful about the path Earl will take in the next 96 hours - in particular, about the longitude band through which it'll pass.

I think the models are overconfident on the low pressure trough developing in the middle of the country being strong enough to push Earl so hard out to see. Depending on how Fiona (I love the names this year btw) speeds up, her push may just be enough with a weaker front to keep Earl close to our shore.

Having lived through Andrew in S Florida, Bertha/Fran/Bonnie/Floyd/and Isabel in Eastern NC, I am done with Hurricanes...

Greg & Co., I apologize if I am late to the party on this one, and can post on an update later as well. I noticed the graphical wind forecast model on Jeff Masters' blog called for tropical storm force winds in the lower Chesapeake Bay. Is there any chance that a distant Earl would be a threat to Tangier or Smith Islands (in the middle of the lower bay), either with wind, tropical rains, or storm surge or any sort?

I'm not sure you read this post very carefully. In my opinion, Greg did a great job mixing in information about the official National Hurricane Center forecast, his own analysis, and also highlighting the overall uncertainty with language such as "Although the weather models are in reasonably good agreement that the upper-level low will arrive in time to deny a direct hit, typical four-day forecast errors (for both tropical cyclones and upper-level lows) are large enough that residents along the East Coast from Jacksonville, Fla., to Cape Cod, Mass., should pay close attention to the situation."

I'm supposed to be meeting my mother in Charlottesville on Friday and driving with her to West Virginia. I'm coming from Northern VA but she is coming from VA Beach and is worried that she won't be able to travel because of Earl. How likely is it that Earl will "attack" the Hampton Roads area? Thanks!

The forecasts for Earl are making me nervous--it seems to be creeping closer and closer to the coast. We're in Coastal DE for the weekend--looks like the red flags will be up all weekend. Here's hoping we don't get a lot of rain and wind, I'm not looking forward to a houseful of people stuck in TS conditions!